Modern elevator installations or so-called fire service elevators, which are designed additionally for this purpose, should provide reliable operation even in the case of fire. On the one hand evacuation of persons and/or material, which is at risk, from the stories affected by the fire should be ensured and on the other hand a functionally capable elevator should be available for the transport of fire service personnel and their extinguishing material. In both cases the use of extinguishing water should not have the consequence that the elevator installation or the fire service elevator no longer functions. This applies not only to the use of a sprinkler installation on a story, but also to the use of extinguishing water by the fire service.
This means that electric components of the elevator installation should remain dry. Moreover, it should be ensured that a support means is still driven as intended on a drive pulley. Extinguishing water can in that case negatively influence the traction of the support means on the drive pulley. On the one hand, extinguishing water can directly reduce the coefficients of friction between the drive pulley and the support means and on the other hand lubricant present in the extinguishing water can in addition negatively influence the traction between the support means and the drive pulley. A support means wetted by extinguishing water can thus lead to a reduction of traction or even to a complete loss of traction. Particularly in the case of a substantial difference between the weight of the elevator cage and a counterweight an uncontrolled travel of the elevator cage can in that case arise, which has to be stopped by safety brakes.
The use of belt-like support means instead of steel cables can have the problem of additionally amplifying the loss of traction between support means and drive pulley. The synthetic material surfaces of belt-like support means sometimes change their traction characteristics in the case of wetting by extinguishing water more strongly than support means of steel cable form. This can make it necessary to conduct away the extinguishing water in controlled manner or to catch it. It can be necessary to prevent traction means sections which co-operate with the drive pulley from being wetted by extinguishing water.
The extinguishing water normally penetrates over the shaft doors of the elevator shaft into the elevator shaft. In that case the extinguishing water flows onto a story floor below the shaft doors through into the elevator shaft.